Foetal development is accompanied by many physiological,

biochemical and hormonal changes which influence the nutrient needs

and the efficiency with which the body utilizes them. The changes include

1. Increased Basal Metabolic Rate (BMR)

Due to foetal growth the BMR increases by about 5 percent in

the 1st trimester reaching a high level of 12 percent during later stages

of pregnancy.

2. Gastro intestinal changes:

Gastro intestinal motility diminishes which may result in

constipation. The acid and pepsin secretion in the stomach is less and

additionally a relaxed lower oesophagal sphincter may cause

regurgitation of stomach contents into the oesophagus leading to

sensation of heartburn and vomiting. This becomes more pronounced

with increasing pressure of the foetus.

In later half of pregnancy the efficiency of absorption of iron,

calcium and B vitamins increases as a natural adaptation mechanism to

meet the increased needs.

3. Hormonal changes:

During pregnancy there is increased secretion of the following

hormones.

• Aldosterone by the adrenal gland.

• Progesterone which relaxes uterine muscles to expand to

accommodate the growing foetus.

• Thyroxin.

• Parathormone.

4. Changes in body fluid

The blood volume expands by 50 percent and this increased

amount of blood is required to carry nutrients to the foetus and remove

metabolic wastes from the foetus.

With increase in blood volume the concentration of